From: Andrew Sullivan <ajs@crankycanuck.ca>
To: pgsql-sql@postgresql.org
Subject: Re: Alternative to serial primary key
Date: Thu, 6 Jul 2006 06:44:06 -0400
Message-ID: <20060706104406.GA26210@phlogiston.dyndns.org> (raw)
In-Reply-To: <12b7ac1e0607060316ub7b5e21i5e8e3bef2504e02c@mail.gmail.com>
References: <12b7ac1e0607060316ub7b5e21i5e8e3bef2504e02c@mail.gmail.com>
On Thu, Jul 06, 2006 at 10:16:42PM +1200, David Clarke wrote:
> column that is calculated from another column in the table but I think
> it would still be more effective than a serial id.
There is the problem that the hash is not proved unique (in fact,
someone has generated collisions on md5). Primary keys have to be
unique, of course.
I _think_ with a hundred columns, you could probably prove (using
brute force, if need be) that the hashes are going to be unique,
assuming the list of possible values in each column is bounded.
A
--
Andrew Sullivan | ajs@crankycanuck.ca
A certain description of men are for getting out of debt, yet are
against all taxes for raising money to pay it off.
--Alexander Hamilton
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To: pgsql-sql@postgresql.org
Cc: ajs@crankycanuck.ca
Subject: Re: Alternative to serial primary key
In-Reply-To: <20060706104406.GA26210@phlogiston.dyndns.org>
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